7T-fMRI: Faster temporal resolution yields optimal BOLD sensitivity for functional network imaging specifically at high spatial resolution

Peter E. Yoo, Sam E. John, Shawna Farquharson, Jon O. Cleary, Yan T. Wong, Amanda Ng, Claire B. Mulcahy, David B. Grayden, Roger J. Ordidge, Nicholas L. Opie, Terence John O'Brien, Thomas J. Oxley, Bradford A. Moffat

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Recent developments in accelerated imaging methods allow faster acquisition of high spatial resolution images. This could improve the applications of functional magnetic resonance imaging at 7 Tesla (7T-fMRI), such as neurosurgical planning and Brain Computer Interfaces (BCIs). However, increasing the spatial and temporal resolution will both lead to signal-to-noise ratio (SNR) losses due to decreased net magnetization per voxel and T1-relaxation effect, respectively. This could potentially offset the SNR efficiency gains made with increasing temporal resolution.We investigated the effects of varying spatial and temporal resolution on fMRI sensitivity measures and their implications on fMRI-based BCI simulations. We compared temporal signal-to-noise ratio (tSNR), observed percent signal change (%(increment). S), volumes of significant activation, Z-scores and decoding performance of linear classifiers commonly used in BCIs across a range of spatial and temporal resolution images acquired during an ankle-tapping task.Our results revealed an average increase of 22% in %(increment)S (p=0.006) and 9% in decoding performance (p=0.015) with temporal resolution only at the highest spatial resolution of 1.5×1.5×1.5mm3, despite a 29% decrease in tSNR (p<0.001) and plateaued Z-scores. Further, the volume of significant activation was indifferent (p>0.05) across spatial resolution specifically at the highest temporal resolution of 500ms.These results demonstrate that the overall BOLD sensitivity can be increased significantly with temporal resolution, granted an adequately high spatial resolution with minimal physiological noise level. This shows the feasibility of diffuse motor-network imaging at high spatial and temporal resolution with robust BOLD sensitivity with 7T-fMRI. Importantly, we show that this sensitivity improvement could be extended to an fMRI application such as BCIs.

Original languageEnglish
Pages (from-to)214-229
Number of pages16
JournalNeuroImage
Volume164
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

  • 7T, fMRI, sensitivity, temporal resolution
  • BCI
  • Classification
  • Physiological noise

Cite this

Yoo, Peter E. ; John, Sam E. ; Farquharson, Shawna ; Cleary, Jon O. ; Wong, Yan T. ; Ng, Amanda ; Mulcahy, Claire B. ; Grayden, David B. ; Ordidge, Roger J. ; Opie, Nicholas L. ; O'Brien, Terence John ; Oxley, Thomas J. ; Moffat, Bradford A. / 7T-fMRI : Faster temporal resolution yields optimal BOLD sensitivity for functional network imaging specifically at high spatial resolution. In: NeuroImage. 2018 ; Vol. 164. pp. 214-229.
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abstract = "Recent developments in accelerated imaging methods allow faster acquisition of high spatial resolution images. This could improve the applications of functional magnetic resonance imaging at 7 Tesla (7T-fMRI), such as neurosurgical planning and Brain Computer Interfaces (BCIs). However, increasing the spatial and temporal resolution will both lead to signal-to-noise ratio (SNR) losses due to decreased net magnetization per voxel and T1-relaxation effect, respectively. This could potentially offset the SNR efficiency gains made with increasing temporal resolution.We investigated the effects of varying spatial and temporal resolution on fMRI sensitivity measures and their implications on fMRI-based BCI simulations. We compared temporal signal-to-noise ratio (tSNR), observed percent signal change ({\%}(increment). S), volumes of significant activation, Z-scores and decoding performance of linear classifiers commonly used in BCIs across a range of spatial and temporal resolution images acquired during an ankle-tapping task.Our results revealed an average increase of 22{\%} in {\%}(increment)S (p=0.006) and 9{\%} in decoding performance (p=0.015) with temporal resolution only at the highest spatial resolution of 1.5×1.5×1.5mm3, despite a 29{\%} decrease in tSNR (p<0.001) and plateaued Z-scores. Further, the volume of significant activation was indifferent (p>0.05) across spatial resolution specifically at the highest temporal resolution of 500ms.These results demonstrate that the overall BOLD sensitivity can be increased significantly with temporal resolution, granted an adequately high spatial resolution with minimal physiological noise level. This shows the feasibility of diffuse motor-network imaging at high spatial and temporal resolution with robust BOLD sensitivity with 7T-fMRI. Importantly, we show that this sensitivity improvement could be extended to an fMRI application such as BCIs.",
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author = "Yoo, {Peter E.} and John, {Sam E.} and Shawna Farquharson and Cleary, {Jon O.} and Wong, {Yan T.} and Amanda Ng and Mulcahy, {Claire B.} and Grayden, {David B.} and Ordidge, {Roger J.} and Opie, {Nicholas L.} and O'Brien, {Terence John} and Oxley, {Thomas J.} and Moffat, {Bradford A.}",
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Yoo, PE, John, SE, Farquharson, S, Cleary, JO, Wong, YT, Ng, A, Mulcahy, CB, Grayden, DB, Ordidge, RJ, Opie, NL, O'Brien, TJ, Oxley, TJ & Moffat, BA 2018, '7T-fMRI: Faster temporal resolution yields optimal BOLD sensitivity for functional network imaging specifically at high spatial resolution' NeuroImage, vol. 164, pp. 214-229. https://doi.org/10.1016/j.neuroimage.2017.03.002

7T-fMRI : Faster temporal resolution yields optimal BOLD sensitivity for functional network imaging specifically at high spatial resolution. / Yoo, Peter E.; John, Sam E.; Farquharson, Shawna; Cleary, Jon O.; Wong, Yan T.; Ng, Amanda; Mulcahy, Claire B.; Grayden, David B.; Ordidge, Roger J.; Opie, Nicholas L.; O'Brien, Terence John; Oxley, Thomas J.; Moffat, Bradford A.

In: NeuroImage, Vol. 164, 01.01.2018, p. 214-229.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - 7T-fMRI

T2 - Faster temporal resolution yields optimal BOLD sensitivity for functional network imaging specifically at high spatial resolution

AU - Yoo, Peter E.

AU - John, Sam E.

AU - Farquharson, Shawna

AU - Cleary, Jon O.

AU - Wong, Yan T.

AU - Ng, Amanda

AU - Mulcahy, Claire B.

AU - Grayden, David B.

AU - Ordidge, Roger J.

AU - Opie, Nicholas L.

AU - O'Brien, Terence John

AU - Oxley, Thomas J.

AU - Moffat, Bradford A.

PY - 2018/1/1

Y1 - 2018/1/1

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KW - BCI

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KW - Physiological noise

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